1. Field of the Invention
This invention relates to an improvement of a slippage preventer for an ignition cable terminal, which is mounted on and secured to an ignition tower of an internal combustion engine.
2. Statement of the Prior Art
Heretofore, an ignition cable terminal to be coupled to an ignition distributor for an internal combustion engine such as a conventional engine, and the like has an electrical insulation construction, since a high voltage is applied to the terminal. An example of a construction of a conventional ignition cable terminal will be described below with reference to FIGS. 3 to 8.
FIG. 3 is a side elevational view of a conventional terminal of an ignition cable. FIG. 4 is a perspective view of a conventional ignition distributor body for an internal combustion engine. FIG. 5 is a perspective view of a conventional slippage preventer for an ignition cable terminal. FIG. 6 is a rear side view taken from arrow VI in FIG. 5. FIG. 7 is a fragmentary cross sectional view of a conventional ignition tower in which a conventional terminal of an ignition cable is mounted. FIG. 8 is a similar view taken from arrow VIII in FIG. 7, illustrating another example.
As shown in FIG. 3, an ignition cable terminal 1 comprises a reverse L-shaped grommet (discap) 3 made of rubber for covering an end of an ignition cable 2 and a male terminal member 4 secured to the grommet 3 so that the member is coaxially aligned with a vertical portion of the grommet 3. The end of the ignition cable 2 is connected to the male terminal member 4 in the grommet 3.
On the other hand, a connecting portion of an ignition device for an internal combustion engine, as shown in FIG. 4, has a plurality of ignition towers 6 provided on an upper portion of a distributor body 5 for the internal combustion engine. The male terminal member 4 is connected to a female terminal member provided in the ignition tower 6 by pushing a lower portion of the grommet 3 of the terminal 1 into a connection hole 6a in the ignition tower 6. A stepped portion 3a at a lower end of the grommet 3 is pressed against the connection hole 6a in the ignition tower 6 and the grommet 3 is secured to the ignition tower 6 in an air-tight condition due to the elastomeric grommet.
However, it is insufficient to prevent the grommet 3 from slipping out of the ignition tower 6 only by way of a compression force of the grommet 3. For example, when the ignition cable is interfered with during inspection of the engine, the terminal 1 tends to slip out of the ignition tower. The terminal also slips out of the tower gradually due to vibration of the engine.
In either case, it is impossible to obtain normal ignition, thus leading to melting of a catalyst for purifying exhaust gas. As the ignition cable carries a high voltage, exposure of its terminal can have serious consequences. For example, if a leakage of volatile gas occures, an explosion or fire may result.
Accordingly, heretofore it is necessary to use a slippage preventer which secures the terminal of the ignition cable to the ignition tower.
As shown in FIGS. 5 and 6, a plastic preventer 7 is provided at the rear thereof with a large opening 7a for receiving the grommet 3 for the terminal 1 for the ignition cable at the front thereof. The preventer 7 is provided with a locking arm 7c having at one end a locking hole 7b for receiving a locking projection formed on the ignition tower 6 as mentioned below and a handle 7d for releasing the preventer 7 from the ignition tower 6.
As shown in FIG. 7, the locking projection 6b provided on the side of the ignition tower 6 engages with the locking hole 7b provided in the preventer 7 so that the head 3b of the grommet 3 is secured in the preventer.
The cylindrical female terminal member 6c, which is provided in the ignition tower 6 and is contact with the male terminal member 4, is connected through a lead (not shown) to an igniter of the internal combustion engine.
In the above conventional preventer 7, however, the mounting direction of the preventer depends on the position of the locking projection 6b on the tower 6 and the direction of the horizontal portion of the grommet 3, i.e., the direction of drawing the cable is limited.
In particular, in the distributor body 5 for igniting the internal combustion engine as shown in FIG. 4, since a plurality of ignition towers 6 are arranged in the upper narrow space the terminal must be connected to the ignition tower 6 so that none of the horizontal portions of the grommet 3 are interfered with. As mentioned above, however, it is very difficult to connect the terminal to the tower if the direction of mounting the grommet 3 is limited by the position of the locking projection 6b.
Further, since a complicated ignition device requires a delicate adjustment of the direction of drawing the cable, the conventional preventer no longer requires such an arrangement.
In order to overcome this problem, it will be possible to predeterminately set the direction of the locking projection 6b so that each of the directions of drawing the cables becomes optimum to each of the ignition towers, respectively. This, however, requires a troublesome machining operation and is unadaptable. It is also possible to provide the preventer 7 with a plurality of locking holes on the periphery thereof and to engage the locking projection 6b with a locking hole provided in a suitable direction. This, however, requires provision of a plurality of locking arms 7c corresponding to the locking holes 7b, causes the preventer to be weakened, and is unadaptable to the fine adjustment of the direction of the cable.
On the other hand, it will be possible to provide the ignition tower 6 with a flared locking projection 6b' around the periphery thereof and to provide the preventer 7 with a locking arm 7f having at an end a latch 7e for engaging with the projection 6b'.
This construction has an advantage in that the direction of mounting is variable since the latch 7e can engage with the flared locking projection in any direction. It is very difficult, however, to form the flared locking projection 6b' on the whole periphery of the ignition tower 6 under a condition in which a die is used to mold the preventer. The flared locking projection 6b' requires a greater distance than the other preventers described above between the ignition towers, and thus makes it difficult to provide many ignition towers in a narrow space above the distributor.